In the case of paraffinic type crude oils, operators have to face the risk of a circulation standstill in the pipe which may lead, depending notably on the time of standstill and on unfavourable temperature conditions, to a certain “solidification” or gelification of the crude in the pipe. In this case, it is clear that the circulation restart conditions can lead to pressures that are extremely delicate to control with local installations. In order to prevent or limit this restart difficulty risk, one may be led to empty the pipes of the paraffinic hydrocarbons and to replace them by simple fluids. This operation involves a considerable production time waste.
One may also be led to dimension the pipes or to provide thermal insulation and/or heating of the pipes so as to increase the time available for a circulation standstill.
Current restart pressure estimations can lead to pointless investment in emptying, pumping pipe, thermal insulation, heating installations, and/or to perform pointless emptying (when possible). It can be noted that, generally, a production pipe can rarely be emptied. This is possible for a planned circulation standstill, if adequate means are available, but it is more rarely possible in unpredictable cases.
The present invention provides a new method of determining the flow restart conditions of paraffinic crudes in pipes. This method both comprises experimental stages and numerical calculation stages.